1. Field of the Invention
The present invention relates to the deflection of laser beams, irrespective as to whether this is implemented within or externally of the laser itself; necessitating the utilization of metal mirrors or reflectors of high-quality which, in short, are hereinbelow designated as laser mirrors or reflectors. Laser mirrors of that type require an extremely good mirror surface, a high reflective capability and a good geometric planicity, as well as a high surface hardness.
2. Discussion of the Prior Art
Metal mirrors or reflectors which are in current use are preferably produced from polycrystalline brass or copper, and through the intermediary of a suitable surface treatment; for instance, such as diamond polishing, are imparted the necessary optical properties. During the treatment of such types of metal mirrors, there is encountered the always closer approach to a natural limitation in the quality of the surface, which is dependent upon the type of material. At a depth in the roughness (peak-to-valley) of the surface, it does not appear to be possible to be able to attain roughness values (surface finish) of below 3 nm (nanometers); through step-wise or gradual formation of the surface on the basis of machining, it is currently not possible to extend below 40 nm in the waviness of the surface. Through these two features, namely, the depth in the surface roughness and the step-wise or gradual formation, there is to a decisive degree determined the optical quality of the mirror surface, and as a result thereof the scattering or divergence of the laser beam. The above-mentioned gradual or step-wise formation is produced through the machining treatment of the surface of a polycrystalline material in that the grains along the surface evade or give way to the machining worktool at different measures, and subsequent to treatment again return into their initial position. In accordance with the material composition and crystal structure there are obtained areas; only visible under a microscope, which are offset stepwise relative to each other along the grain boundaries.
Any overcoming of the above-mentioned limitations, pursuant to the current state-of-the-technology regarding such processing machines, appears only to be possible through the employment of new materials for the mirrors.